1. Field of the Invention
The present invention relates to an amplitude sensitive damper apparatus, and more particularly to an amplitude sensitive damper apparatus that varies a damping force characteristic according to a wheel stroke (amplitude) size of a vehicle.
2. Description of Related Art
Generally, a damper absorbs a repellent force of a spring to improve the close contacting property between a tire and the road and to reduce the rolling of the vehicle body so that driving safety of the vehicle can be enhanced.
Then, if the damping force is much higher than the repellent force of the spring, there is a problem in which the damper restricts the elastic deformation of the spring such that the spring does not normally operate.
FIG. 1 is a cross-sectional view of general amplitude sensitive damper apparatus.
As shown in FIG. 1, an outer case 101 and an inner case 103 are provided, operating oil is charged therein, and a piston rod 105 and a piston valve 107 that is mounted thereon are installed inside the inner case 103 to move up and down while generating a damping force through the operating oil.
The piston valve 107 divides the inner case 103 into upper and lower oil chambers C1 and C2, and a fixed piston valve 109 is provided in the lower portion of the inner case 103 to compensate the volume variation.
Further, an amplitude sensitive valve unit 111 is constituted on the piston rod 105 in the upper side of the piston valve 107 to vary the damping force characteristic according to the wheel stroke size of the vehicle such that ride comfort and handling stability can be improved.
Upper and lower retainers 113 and 115 are mounted on the upper and lower sides of the piston valve 107, an amplitude sensitive valve 117 is slidably mounted on the piston rod 105 between the upper and lower retainers 113 and 115, and the upper end and the lower end thereof are respectively supported by inner and outer springs S1 and S2.
Here, if the movement of the piston rod has a high amplitude, the amplitude sensitive valve 117 generates a high damping force, and if the movement thereof has a low amplitude, the amplitude sensitive valve 117 generates a low damping force.
However, when the piston rod swings with the high amplitude, there is a drawback in that impact noise is generated between the retainer 113 and the amplitude sensitive valve 117, and the inner and outer springs S1 and S2 are applied in the upper and lower portions of the amplitude sensitive valve 117 such that the overall weight and the production cost are increased.
Also, the inner and outer springs S1 and S2 are applied in the upper portion and the lower portion of the amplitude sensitive valve 117 such that there is a problem in that the overall length of the amplitude sensitive valve unit 111 becomes longer.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.